1. Field of the Present Invention
The present invention is a continuous strong thread closure assembly which is designed to achieve optimum thread engagement with a minimum amount of turning of the cap.
2. Description of the Prior Art
Continuous thread bottle and container assemblies are well known to persons of ordinary skill in the art. In general, it is quite common for the container to have a sloping, continuous thread finish which has a constant thread diameter from top to bottom. The screw cap can, preferably, have a compressible liner on the inside of its top and has a counterpart thread configuration to that of the container on the inside surface of its skirt. Such conventional designs call for direct engagement of the lowest thread portion of the cap with the uppermost thread portion of the container. Such conventional screw cap/container assemblies require a substantial amount of turning of the cap before there is optimum thread engagement and, optionally, liner compression to seal the assembly.
The present invention is directed to a modified continuous thread closure assembly which achieves optimum thread engagement with a lessened amount of turning of the cap. It is a distinct consumer advantage and yet provides a closure assembly which has good sealing properties.
The prior art known to the present inventor does not appear to suggest the present invention and has never been practiced commercially. For example, U.S. Pat. No. 650,429 shows a refillable gas capsule having a "frustoconical" threaded neck which is described as having unspecified conveniences in manufacture and in applying a cap thereto. This patent fails to teach a closure assembly wherein the screw cap has a counterpart thread configuration such that the lowest thread portion on the cap passes the uppermost thread portion on the container so as to be engageable with a lower thread portion on the container to allow for more than one full turn of thread engagement between the threads on the cap with less than one turn of the cap.
U.S. Pat. No. 759,168 shows a jar closure which contains a rubber ring between the cap and the container finish. This fails, for example, to suggest the present modified closure assembly which has direct engagement between the threads on the container and the cap.
U.S. Pat. No. 3,297,187 shows closure devices for containers, jars and the like which have a tapered shape for the contacting surfaces on the cap and the jar. The closure member in this patent is applied to the container by pushing down, by hand, rather than by rotation of the cap onto the jar as in the present invention.
German published application 2,323,561 discloses a closure having a multiple thread turns of a saw-tooth profile and a taper cone angle of 30 degrees. The closure can be firmly closed with a half turn. The closure occurs by way of a depression in the cap plugging the hole in the neck of the container. The many saw-tooth profile threads of the device disclosed in the German application tend to chip and are not inherently strong.
It is an object of the present invention to provide a closure which is inherently strong, does not chip easily and can provide two full turns of thread engagement with less than one turn of the cap.